In tunnels, mines and underground works in general the presence of water and excess humidity creates considerable problems, whether during the various phases of construction or throughout the life of the work or infrastructure.
The hazards that arise due to the formation of puddles or ice on traffic-bearing surfaces are well known. Similarly, in railway tunnels water is also a danger for the installations, and in regions with very low winter temperatures the formation of ice can break the track by deformation and even prevent the passage of trains.
In any underground construction work, infiltrations of water damage the complex control equipment and operating services, and the reinforced concrete structures often require special treatment to prevent them decalcifying and subsequently expanding due to oxidation of frameworks.
Conventional waterproofing systems resolve many of the aforementioned problems, but their costs are generally high. This is shown particularly when there arise difficulties such as high infiltrations of rain during application of the waterproofing, extreme climatological conditions, and even the need for waterproofing after the building work has been completed.
A type of coating is currently used which consists in sheets made of plastic material, and more specifically PVC. Said sheets have the disadvantage that their PVC content means that they are not biodegradable, while they also have low thermal gaps and low resistance to chemical agents.
Similarly, for several years now the roofs or terraces of buildings have also been waterproofed with PVC sheets or asphalt sheets to protect them from water. However, owing to the materials used in said sheets and the climatological conditions and exposure to sunlight, the sheets undergo ageing and deterioration, which means that they have to be checked and repaired.
Spanish patent no. 9600657, whose holder is the same as that of this patent application, describes a coating or waterproofing sheet, particularly for tunnels, made up of three layers: a first layer of raffia, a second intermediate layer of foam and a third layer of plastic material metallised with aluminium. This sheet has the advantage that the foam is not inflammable and its mechanical strength is higher than that of PVC sheets.
But this type of sheet has the disadvantages of only being applicable in tunnels or channels and showing rapid ageing, which means that the sheet has a short working life.